Acoustic wave devices manufactured by arranging electrodes on a composite substrate including a support substrate and a piezoelectric substrate that are bonded together have been known. The acoustic wave devices are used as, for example, band-pass filters in communication devices, such as mobile phones. In known composite substrates, the piezoelectric substrate is formed of lithium niobate, lithium tantalate, etc., and the support substrate is formed of silicon, quartz, etc. (see Patent Document 1).